Method of and means for screen venting a core box



2,914,821 Patented Dec. 1, 1959 This inventionrelates gene rally toshell molding, and,

more particularly, to a novel and improved method of and means for venting a corebox for shell molding.

wIn the past, when making sand cores for casting purposes the core was made in a c'orebox, that is, formed to the desired shape in the corebox, and then'itwas taken 1 United States Patent" Ofiice structure illustrated in Fig. 2, taken along the line 44 thereof;

Fig. 5 is a fragmentary elevational sectional view of a corebox having a shaped inner surface and provided with a vent made in accordance with the invention;

Fig. 6 is a broken, fragmentary elevational sectional 7 view of a corebox provided with a vent means in accordance with the invention;

Fig. 7 is a fragmentary elevational sectional view of a prior art type corebox screen vent; and

Fig. 8 is an end view of the screen vent illustrated in Fig. 7, taken along the line 8-8 thereof, and looking in the direction of the arrows.

Referring now to the drawings, and in particular to Figs. 1 through 4, the numeral 10 generally designates a corebox of the type used in shell molding. The corebox 10 includes the usual bottom, top, and side Walls 11, 12,

out and baked. The aforementioned method of making v cores has beenreplaced in the past few years by a method of core making called in the art shellmolding. In the latter mentioned methodthe shell core is baked in the 1 corebox. The sand mixture employed in making shell cores is delivered tothe core'boxflby means offorced 1 At present, the coreboxes used in shell molding are provided with vents employing wire mesh screen's which cl'og up in ashort time, that is, in a matter of aday or less 1 r The screen then must betaken-out ahdcleaned and this results in much down time with a further resultant loss or production output and money. Furthermore, during the baking processthe sand mixture is baked onto I tne screens and the corebox" cannot be properly vented.

Such action results in the sand not being packed firmly in the corebox and a spongy core is produced. .Then when such a spongy core is used in a casting operation the-resultant casting will have fuzzy protrusions around the surfaces thereof and such castings have to be scrapped.

It. is an importantobject of this invention to provide 13 and 14, respectively. The 'corebox 10 also includes end walls as 15 at each end thereof. The corebox 10 is provided with the usual inlet conduits as 16 through which is delivered by means of forced air the sand mixture for making the core. The corebox 10 may be provided with a shaped lining or wall section as 17 along the inner faces of the corebox walls. When used in the claims in this application, the term corebox wall istaken to include this lining or wallsection 17.

The numeral 18 generally designates a corebox vent made in accordancewith the principles of the invention. A corebox provided with the vent 18 would have a plurality of these vents disposed in the walls thereof and at the positions 'most optimum for venting. The vents 18 are mounted in the walls ofthe corebox as shown in Fig.

l.- For each vent '18 a hole-as 19 would be bored in the corebox wall to a diameter slightly less than the diameter of the circular vent 18. That is, the diameter of the vent 18 overall would be approximately .002 larger than the hole 19; The vent 18 is then press fitted into the hole 19.

a method of and means tor'screen venting acorebox during a shell molding operation whereby the corebox may be efficiently and properly vented so as to permit the sand'mixture to be completely packed to produce a'solid or homogeneous core. a i i The vent 18 includes the cylindrical body 20 having the innerend 21 which is adapted to be disposed level or even with the inner surface of the wall of the corebox in which it is disposed. The body 20 is provided with an axial aperture therethrough which tapers outwardly or diverges 'It is; another object of this invention toiprovide anovel vent for a corebox -which is simple and ruggedin construction, economical"offmanufacture, and efficient in operation. i I

It is a further object of 'thisinvention'to-provide-a novel vent for a corebox adapted foruse in a shell molding operation 'which is self cleaning' and' which maybe mounted to vent any desired shape orangle ,formed by v the inner surface of, the coreb ox w hich determines the shape of the coreto be'producedi e V -Other objects, features and advantages of this invention will be apparent from the following detailed description and appended claims, reference being had to the accompanying drawings forming a part of the specification wherein like reference numerals designate corresponding parts of the several views.

In the drawings:

Fig. 1 is an elevational sectional view of a shell molding corebox provided with vents made in accordance with the principles of the invention;

Fig. 2 is a side elevational view of a vent embodying the invention;

Fig. 3 is an end view of the structure illustrated in Fig. 2; taken along the line 3-3 thereof, and looking in the direction of the arrows;

Fig. 4 is an .elevational central sectional view of the outwardly from the inner end 21 of the body 20 to the outer end" 24 thereof. The diverging hole through the body 20 diverges. from the circular opening 22 at the inner end of the body 20 to the larger circular opening 23 at the outer end of thebody 20. A preferred angle of divergence for this hole is 5 as indicated in Fig. 4.

Centrally mounted, or axially disposed, within the hole through the body 20 is a truncatedpin generally indicated by the numeral 25. The inner end 26 of pin 25' is adapted to be even or level with the inner end 21 of the body 20; The inner'end 2 6 of the pin 25 is disposed concentrically with the'inner end 22 of the hole through the body 20.

The outer surface 27 of the pin 25 converges outwardly, I

g or tapers outwardly ofth'e' -corebox but inwardly'to wards' the axis of the. pin 25; A preferred'angle of convergence for the pin 25 is 5 as indicated in Fig. 4. The inner end 26 of the pin 25 is preferably disposed in the hole in the body 20 with a peripheral clearance therebetween of .005. The outer end of the pin 25 is integrally connected, preferably, to the one end of a semi-circular arm 29 and the other end of this arm 29 is fixedly connected by any suitable means to the outer end of the body 20. It will be understood, that the vent 18 may be made to any desired size. The body 20 of the vent 18 is preferably made from cold rolled steel and the inner surface thereof is preferably highly polished to as fine a microfinish as possible. The surface 27 of the pin 25 is also preferably highly polished to a fine micro-finish. The pin 25 may be formed from any suitable metal, as piano wire, spring wire or drill rod. The arm 29 would be formed from the same material as the pin 25.

In operation, the air forcing the sand mixture into the corebox will. beventedto the atmosphere through the clearance around the pin 25. The arm 29 functions as a spring and may be called a spring arm whereby, when the air is vented through the body the pin vibrates in the body 20 and-permits venting of the air but prevents the sand mixture from being blown out of the corebox 10. The vent 18 thus accomplishes a screening action or function without the serious defects of the prior art type vent screens. The vibrating pin 25 avoids any stoppage of air venting and will not become plugged up.-

Figs. 7 and 8 merely show a. prior art type screen vent used in shell molding which has a serious defect in that it plugs up easily and quickly. The numeral indicates the cylindrical hollow body of the vent which is provided at the inner end thereof with a lip 31 and against the Fig. 6 illustrates the mounting of a vibratory pin 25b directly in a diverging hole 34 formed in the corebox wall of the corebox 101'). In this embodiment of the invention the spring arm 29b would be fixedly mounted by any suitable means directly in the corebox wall. The hole 34 would taper outwardly from the inner surface of the corebox to the outer surface thereof. The degree of tapers of the hole 34 and the pin 25b, and the clearance between the inner end of the pin'25b would be the same as given hereinbefore for the embodiment of Figs. 1 through 4.

If it is desired to enlarge the clearance between the inner end of the pins 25 this may be easilyaccomplished by merely springing the pins 25 inwardly and grinding off a portion to provide the desired increased clearance.

While it will be apparent that the preferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated,'it will be appreciated that the invention is susceptible to modificatiomvariation and change without departing from. the proper scope or fairmeaning of the subjoined claims.. 1

It will be seen, that the present invention includes the method of screen venting a corebox during the. making of a shell core. The corebox would first be provided with an outwardly diverging hole through a wall of the corebox and this-hole may be formed either. directly in .a wall of the corebox or in a separate body'mounted in a wall of the corebox. A freely vibratory outwardly converging centrally located pin is then disposed in said diverging hole and is operatively held in said hole by means of a spring arm having one endthereof fixedly connected to the pin and the other end thereof-fixedly connected to either the corebox or to the body.

What I claim is: p

l. A method of screen venting a corebox during the making of a shell core comprising the steps of: first, providing an outwardly diverging hole through a wall of the corebox; and, second, mounting a freely vibratory outwardly converging centrally located pin in said diverging hole, whereby, air can be freely vented through said hole past said pin and the core sand will be retained in said corebox.

2. In combination; a sh'e1l"rnold'ing corebox provided with an outwardly diverging hole through awall thereof; an outwardly converging centrally located pin disposed in said innerend thereof even with the inner end of said hole and being concentrically spaced therefrom; and, means for retaining the pin in said hole in a freely vibratory condition.

3. The invention as set forth in claim 2, wherein: said outwardly, diverging hole is formed in a wall of the corebox.

4. The invention as set; forth in claim 2, wherein: said outwardly diverging hole is formed in a separate body mounted in a wall of the corebox.

5.. In. combination, a shell molding corebox provided with an outwardly diverginghole through a wall thereof; an outwardly converging centrally located pindisposed in said inner end thereof even with the inner end of said hole and: being concentrically spaced therefrom; and, a spring arm having one end thereof fixedly connected to the corebox and. the other end thereof fixedly connected to the. pin. for retaining the pin in said hole in a freely vibratory condition.

6. In combination, a shell molding corebox provided with anoutwardly diverginghole through a wall thereof; an outwardly converging centrally located pin disposed in said inner end thereof even with the inner end of said hole and, beingv concentrically spaced therefrom; said outwardly diverging hole being formed in a separate body mounted ina wall of the corebox; and,, a spring arm having one end thereof fixedly mounted to the outer end of said body and the other end thereof fixedly mounted to the pinfor retaining the pin in said hole'in a freely vibratory condition.

7. A vent for a shell molding corebox comprising: a body having a hole therethrough with said hole diverging from one end of the body toward the other end of the body; a centrallylocated pin disposed in said hole in said body; said pin being truncated in shape with the larger end thereof being concentrically disposed in the smaller end of said diverging hole and being concentrically spaced therein; and, means for retaining the pin. in said hole ina freely vibratory condition.

8. The invention as defined in claim 7, wherein: said meanscomprisesi a spring arm having one end thereof fixedly connected. to the smaller end of saidtruncated pin and the other end thereof fixedly connected to the body.

Demmler- Aug. 9, 1938 Copeland- Sept. 20, 1949 

